A polypropylene composite material and its preparation method and application

Abstract

The present invention relates to a polypropylene composite material and a preparation method and application thereof. The polypropylene composite material comprises the following components in parts by weight: 100 parts of polypropylene resin, 1 to 5 parts of scratch resistant agent, and 9 to 56 parts of cycloolefin polymer modified carbon fiber. The polypropylene composite material has high hardness, high impact strength, high gloss and good scratch resistance.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and more specifically to a polypropylene composite material and a preparation method and application thereof. Background Art

[0002] Polypropylene is widely used in automobiles due to its low density, high cost performance, excellent heat resistance, rigidity, chemical resistance, easy processing and recycling, and has become the largest and fastest growing variety of automotive plastics. In recent years, the rapid development of the automotive industry has put forward higher and higher requirements for interior and exterior materials, such as high strength, impact resistance, scratch resistance, and good dimensional stability for instrument panels, door panels, and bumpers.

[0003] Since the surface of polypropylene materials is easily scratched by external forces, it will greatly affect the appearance of the products and limit its wide application in automotive interior products. At present, most of them are improved by adding scratch-resistant agents to improve the scratch resistance of polypropylene materials. For example, patent CN108504023A adds scratch-resistant agents to improve the scratch resistance of materials. However, excessive addition of scratch-resistant agents will have a negative impact on the mechanical properties of polypropylene materials. Therefore, the amount of scratch-resistant agents added is limited, and the improvement of the scratch resistance of polypropylene materials is limited.

[0004] In addition, for parts such as instrument panels and door panels, polypropylene materials are also required to have a higher gloss.

[0005] Based on the above situation, it is necessary to develop polypropylene materials with good mechanical properties, scratch resistance and high gloss to expand the application of polypropylene materials in automotive interior products. Summary of the invention

[0006] The primary purpose of the present invention is to overcome the problems of poor mechanical properties, scratch resistance or glossiness of polypropylene materials in the current technology and to provide a polypropylene composite material.

[0007] A further object of the present invention is to provide a method for preparing the above polypropylene composite material.

[0008] A further object of the present invention is to provide application of the above polypropylene composite material in the preparation of automobile parts.

[0009] The above-mentioned object of the present invention is achieved by the following technical solutions:

[0010] A polypropylene composite material comprises the following components in parts by weight:

[0011] 100 parts of polypropylene resin,

[0012] 1 to 5 parts of anti-scratch agent,

[0013] 9 to 56 parts of cycloolefin polymer-modified carbon fibers.

[0014] The inventor of the present invention has found through research that adding cycloolefin polymer modified carbon fiber to polypropylene resin can improve the hardness, impact strength and glossiness of polypropylene composite materials, and can also work together with scratch resistance agents to improve the scratch resistance of polypropylene composite materials. The reason is that there are flexible aliphatic hydrocarbon segments and rigid cyclic structures in cycloolefin polymers, and the aliphatic hydrocarbon segments can make the cycloolefin polymer and the polypropylene matrix have good compatibility; the rigid cyclic structure can give the material certain optical properties; and after the carbon fiber is modified by cycloolefin polymers, the carbon fiber is easy to migrate to the outer layer of the polypropylene composite material under the action of the cycloolefin polymer and the shear force during the processing, thereby improving the crystallization performance of the surface layer, and the polypropylene composite material contains more non-crystalline areas, making the polypropylene composite material a material that is tough on the outside and tough on the inside; and the improvement of the crystallization performance of the outer layer of the polypropylene composite material can work together with the scratch resistance agent to improve the scratch resistance of the polypropylene composite material.

[0015] That is, the polypropylene composite material of the present invention has high hardness, high impact strength, high glossiness and good scratch resistance.

[0016] In the present invention, the polypropylene resin is used as the matrix resin, and its content usually accounts for more than 60wt% of the polypropylene composite material.

[0017] Optionally, the polypropylene resin is at least one of homopolymer polypropylene, random copolymer polypropylene or block copolymer polypropylene.

[0018] Preferably, the polypropylene resin is block copolymer polypropylene.

[0019] Optionally, the melt mass flow rate of the polypropylene resin at 230° C. and a load of 2.16 kg is 10 to 50 g / 10 min.

[0020] In the present invention, the melt mass flow rate of the polypropylene resin can be measured according to ISO 1133-1:2011.

[0021] The commonly used anti-scratch agents in the art can be applied to the present invention.

[0022] Optionally, the anti-scratch agent is at least one of silicone powder, oleamide or erucamide.

[0023] The weight proportion of the cycloolefin polymer modified carbon fiber added to the polypropylene composite material can be 10 parts, 15 parts, 20 parts, 25 parts, 30 parts, 35 parts, 40 parts, 45 parts, 50 parts or 55 parts.

[0024] Optionally, the mass fraction of the cycloolefin polymer modified carbon fiber relative to the polypropylene resin is 10-55%.

[0025] Preferably, the mass fraction of the cycloolefin polymer modified carbon fiber relative to the polypropylene resin is 25-55%. Within this range, the obtained polypropylene composite material has better properties.

[0026] Optionally, the cycloolefin polymer in the cycloolefin polymer-modified carbon fiber is at least one of a cycloolefin copolymer and a cycloolefin homopolymer.

[0027] Optionally, the cycloolefin copolymer is a copolymer of ethylene and a cycloolefin monomer.

[0028] Optionally, the cycloolefin monomer of the cycloolefin polymer is at least one of cycloheptene or bicycloheptene.

[0029] Optionally, the cycloolefin polymer has a glass transition temperature Tg of 70 to 150°C.

[0030] In the present invention, the glass transition temperature Tg of the cycloolefin polymer can be measured by a differential scanning calorimeter.

[0031] Optionally, the cycloolefin polymer modified carbon fiber is prepared by modifying hydroxylated carbon fiber using a cycloolefin polymer and a coupling agent; the cycloolefin polymer modified carbon fiber is prepared by the following method: adding hydroxylated carbon fiber, a coupling agent and a cycloolefin polymer to a solvent, reacting at 70 to 100° C. for 4 to 8 hours to obtain the cycloolefin polymer modified carbon fiber.

[0032] Generally, the mass ratio of the hydroxylated carbon fiber, the coupling agent and the cycloolefin polymer is 1:(0.2-0.8):(0.2-0.8).

[0033] Generally, the coupling agent is a silane coupling agent; the silane coupling agent includes but is not limited to at least one of γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, vinyltriethoxysilane or vinyltrimethoxysilane.

[0034] Generally, the solvent includes but is not limited to at least one of N,N-dimethylacetamide, cyclohexanone, p-xylene, N,N-dimethylaniline or chlorobenzene.

[0035] Generally, the reaction is carried out in the presence of a catalyst; the catalyst includes at least one of cuprous bromide, ferrous chloride, ferrous bromide or lithium molybdate; the amount of the catalyst added is: 1 to 3 g of catalyst is added for every 100 g of hydroxylated carbon fiber.

[0036] Hydroxylated carbon fibers can be obtained commercially, or prepared by commonly used hydroxylation methods in the art; commonly used hydroxylation methods include but are not limited to liquid phase oxidation, gas phase oxidation or anodic electrolytic oxidation.

[0037] Preferably, the hydroxylated carbon fiber is prepared by the following method: adding the carbon fiber to concentrated nitric acid, reacting at 70-90°C for 4-6 hours to obtain acidified carbon fiber; adding the acidified carbon fiber to tetrahydrofuran, adding a catalyst (sodium borohydride), reacting at 70-90°C for 2-4 hours to obtain hydroxylated carbon fiber.

[0038] More preferably, the average diameter of the cross section of the carbon fiber is 5-10 μm.

[0039] More preferably, the dosage ratio of the acidified carbon fiber to tetrahydrofuran is 1 g: (50-80) mL; the mass ratio of the acidified carbon fiber to the catalyst is 1: (0.02-0.04).

[0040] Preferably, the polypropylene composite material further comprises 1 to 10 parts of other additives.

[0041] Optionally, the other auxiliary agent is at least one of a flame retardant, an antioxidant or an antistatic agent.

[0042] The flame retardants, antioxidants and antistatic agents commonly used in the art can be used in the present invention.

[0043] Optionally, the flame retardant includes but is not limited to at least one of an organic silicon flame retardant, a nitrogen phosphorus flame retardant or a hydroxide flame retardant.

[0044] Optionally, the antioxidant includes but is not limited to hindered phenol and / or phosphite antioxidants.

[0045] Optionally, the antistatic agent includes but is not limited to at least one of an ethoxylated amine antistatic agent, an ionic liquid antistatic agent, a fatty acid salt antistatic agent, a stearic acid monoglyceride antistatic agent or a stearic acid diethanolamide antistatic agent.

[0046] The preparation method of the polypropylene composite material comprises the following steps: mixing the components, melt-extruding, and granulating to obtain the polypropylene composite material.

[0047] Preferably, the temperature of the melt extrusion is 170-220° C., the screw speed is 400-600 rpm, and the screw aspect ratio is (40-60):1.

[0048] The application of the above-mentioned polypropylene composite material in the preparation of automobile parts is also within the protection scope of the present invention.

[0049] Generally, the automobile parts are instrument panels, door panels or bumpers.

[0050] Compared with the prior art, the present invention has the following beneficial effects:

[0051] The polypropylene composite material of the invention has high hardness, high impact strength, high glossiness and good scratch resistance. DETAILED DESCRIPTION

[0052] In order to more clearly and completely describe the technical solution of the present invention, the present invention is further described in detail through specific embodiments below. It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention. Various changes can be made within the scope of the rights of the present invention.

[0053] Some of the reagents selected in the embodiments and comparative examples of the present invention are described as follows:

[0054] Polypropylene resin 1#: copolymerized polypropylene resin, 230°C, 2.16kg, melt mass flow rate of 10g / 10min, EP300M, purchased from Sinopec;

[0055] Polypropylene resin 2#: copolymerized polypropylene resin, 230°C, 2.16kg, melt mass flow rate 50g / 10min, EP5075X, purchased from Sinopec;

[0056] Polypropylene resin 3#: homopolymer polypropylene resin, 230°C, 2.16kg, melt mass flow rate 50g / 10min, H9018, purchased from Sinopec;

[0057] Polypropylene resin 4#: block copolymer polypropylene, 230°C, 2.16kg, melt mass flow rate of 10g / 10min, K9010, purchased from Taiwan Chemical;

[0058] Scratch resistant agent 1#: silicone powder, commercially available;

[0059] Scratch resistant agent 2#: oleamide, commercially available;

[0060] Carbon fiber: PX35CA0250-65, with an average cross-sectional diameter of 7 μm, purchased from Toray, Japan;

[0061] Cyclic olefin polymer 1#: COP, TOPAS 8007F-04, Tg = 78°C, purchased from Polyplastics, Japan;

[0062] Cycloolefin polymer 2#: COP, ZEONEX 330R, Tg = 123°C, purchased from Zeon, Japan;

[0063] Cycloolefin polymer 3#: COP, ZEONOR 1020R, Tg = 102°C, purchased from Zeon, Japan;

[0064] Maleic anhydride-styrene copolymer: maleic anhydride content of 8 wt%, Tg = 116 ° C, purchased from Polyscope;

[0065] Silane coupling agent: γ-aminopropyltriethoxysilane, commercially available;

[0066] Cycloolefin polymer modified carbon fiber 1#, homemade, the preparation process is as follows:

[0067] 1) Hydroxylation of carbon fiber

[0068] 1.1) Add 1 g of carbon fiber to 50 mL of 65% concentrated nitric acid, reflux at 80° C. for 5 hours, wash with deionized water until neutral, and then dry in a vacuum drying oven at 80° C. for 24 hours to obtain acidified carbon fiber;

[0069] 1.2) 1 g of the acidified carbon fiber was added to 65 mL of tetrahydrofuran, and then 0.03 g of catalyst I (sodium borohydride) was added, and the mixture was refluxed at 70°C for 3 hours. After the reaction, the mixture was washed with tetrahydrofuran 4 times and dried in a vacuum drying oven at 80°C for 24 hours to obtain hydroxylated carbon fiber;

[0070] 2) Cycloolefin polymer modification

[0071] The hydroxylated carbon fiber obtained in step 1) is added to a mixed solvent containing a silane coupling agent and a cycloolefin polymer 1# (the weight ratio is hydroxylated carbon fiber: cycloolefin polymer: silane coupling agent = 1:0.5:0.5, and the solvent is N,N-dimethylacetamide), and a catalyst cuprous bromide is added (the addition amount is 2% of the weight of the hydroxylated carbon fiber), and the mixture is reacted at 100°C for 6h. The product is washed 4 times with tetrahydrofuran and filtered, and then placed in a vacuum drying oven at 80°C and dried for 24 hours to obtain a cycloolefin polymer modified carbon fiber 1#, recorded as COP-CF1#.

[0072] Cycloolefin polymer modified carbon fiber 2# is self-made. The preparation process is basically the same as that of COP-CF1#, except that: in step 2), cycloolefin polymer 1# is replaced by cycloolefin polymer 2#; the obtained cycloolefin polymer modified carbon fiber 2# is recorded as COP-CF2#

[0073] Cycloolefin polymer modified carbon fiber 3# is homemade, and the preparation process is basically the same as COP-CF1#, except that: in step 2), cycloolefin polymer 1# is replaced by cycloolefin polymer 3#; the obtained cycloolefin polymer modified carbon fiber 3# is recorded as COP-CF3#.

[0074] Cycloolefin polymer modified carbon fiber 4# is homemade, and the preparation process is basically the same as that of COP-CF1#, except that: in step 2), hydroxylated carbon fiber: cycloolefin polymer 1#: silane coupling agent are weighed in a mass ratio of 1:0.2:0.2; the obtained cycloolefin polymer modified carbon fiber 4# is recorded as COP-CF4#.

[0075] Cycloolefin polymer modified carbon fiber 5# is homemade, and the preparation process is basically the same as that of COP-CF1#, except that: in step 2), hydroxylated carbon fiber: cycloolefin polymer 1#: silane coupling agent are weighed in a mass ratio of 1:0.8:0.8; the obtained cycloolefin polymer modified carbon fiber 5# is recorded as COP-CF5#.

[0076] Coupling agent modified carbon fiber 1#: homemade, the preparation process is basically the same as COP-CF1#, the difference is: in step 2), no cycloolefin polymer is added; the weight ratio is: hydroxylated carbon fiber: silane coupling agent = 1:0.5.

[0077] Maleic anhydride-styrene copolymer modified carbon fiber is homemade, and the preparation process is basically the same as COP-CF1#, except that: in step 2), cycloolefin polymer 1# is replaced by maleic anhydride-styrene copolymer.

[0078] Other additives 1#: antioxidant, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, commercially available;

[0079] Unless otherwise specified, the components (such as other auxiliary agent 1#) selected in each parallel example and comparative example are the same commercially available products.

[0080] The polypropylene composite materials of the embodiments and comparative examples of the present invention are prepared by the following preparation method:

[0081] Weigh each component according to the formula, mix evenly, melt blend and extrude granules through a twin-screw extruder to obtain a polypropylene composite material. The temperatures of each zone of the twin-screw extruder are (from the feeding section to the die) 170°C-180°C, 200°C-210°C, 200°C-210°C, 210°C-220°C, 210°C-220°C, 205°C-210°C, 205°C-210°C, 205°C-210°C, 200°C-210°C, 200°C-210°C. The screw speed of the twin-screw extruder is 500rpm, and the screw aspect ratio is 48:1.

[0082] The properties of the polypropylene composite materials provided in the embodiments and comparative examples of the present invention were measured according to the following test methods:

[0083] (1) Rockwell hardness (HCR): GB / T3398.2-2008;

[0084] (2) Scratch resistance: The grid scratch test method is to draw a grid on the material surface with a fixed load and spacing, and then record and evaluate the color change of the scratches. The scratch resistance of the material surface is characterized by the degree of whitening of the scratches. The grid is drawn using the Yilixin cross-cut tester with a load of 10N. The L value (reflecting the depth of the color) before and after scratching is tested with a colorimeter, and ΔL is calculated. The larger the ΔL value, the more obvious the whitening of the color after scratching, and the worse the scratch resistance of the material;

[0085] (3) Notched impact strength: tested in accordance with GB / T 1843-2008, notch type A;

[0086] (4) Surface gloss: measured according to the standard ASTM D523-2014 using a gloss tester at a test angle of 60°.

[0087] Examples 1 to 14

[0088] Examples 1 to 14 provide a series of polypropylene composite materials, whose formulations are shown in Tables 1 and 2.

[0089] Table 1 Formulas of Examples 1 to 7 (parts by weight)

[0090]

[0091] Table 2 Formulas of Examples 8 to 14 (parts by weight)

[0092]

[0093] Comparative Examples 1 to 4

[0094] Comparative Examples 1 to 4 provide a series of polypropylene composite materials, and their formulations are shown in Table 3.

[0095] Table 3 Formulas of Comparative Examples 1 to 4 (parts by weight)

[0096]

[0097] The properties of the polypropylene composite materials of each embodiment and comparative example were measured according to the above-mentioned test method. The test results are shown in Table 4.

[0098] Table 4 Performance test results of polypropylene composite materials of various embodiments and comparative examples

[0099]

[0100]

[0101] From Table 4, we can see that:

[0102] The Rockwell hardness of the polypropylene composite materials of Examples 1 to 14 is all above 100, the ΔL in the scratch resistance test is all less than 0.6, and the impact strength is all greater than 8.2 kJ / m 2 , the surface glossiness is greater than 76, indicating that the polypropylene composite material of the present invention has high hardness, high impact strength, high glossiness and good scratch resistance.

[0103] In Comparative Example 1, cycloolefin polymer was added, and the surface hardness, impact strength and glossiness of the obtained polypropylene material were not good.

[0104] In Comparative Example 2, carbon fibers modified only by coupling agents but not by cycloolefin polymers were added, and the resulting polypropylene material had poor surface hardness, scratch resistance, impact strength and glossiness.

[0105] In Comparative Example 3, carbon fibers modified with maleic anhydride-styrene copolymer were added, and the obtained polypropylene material had no surface hardness, poor scratch resistance, poor impact strength, and poor gloss.

[0106] In Comparative Example 4, no anti-scratch agent was added, and the obtained polypropylene material had very poor scratch resistance, poor impact strength and poor gloss.

[0107] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A polypropylene composite material, characterized in that: The composition comprises the following components in parts by weight: 100 parts of polypropylene resin, 1~5 parts of anti-scratch agent, 9-56 parts of cycloolefin polymer modified carbon fiber; The melt mass flow rate of the polypropylene resin at 230° C. and 2.16 kg load is 10 to 50 g / 10 min; The scratch-resistant agent is at least one of silicone powder, oleamide or erucamide; The cycloolefin polymer modified carbon fiber is prepared by the following method: adding hydroxylated carbon fiber, coupling agent and cycloolefin polymer into a solvent, reacting at 70 to 100° C. for 4 to 8 hours, thereby obtaining the cycloolefin polymer modified carbon fiber; The cycloolefin monomer of the cycloolefin polymer is at least one of cycloheptene and bicycloheptene.

2. The polypropylene composite material according to claim 1, characterized in that: The polypropylene resin is at least one of homopolymer polypropylene, random copolymer polypropylene or block copolymer polypropylene.

3. The polypropylene composite material according to claim 1, characterized in that: The cycloolefin polymer in the cycloolefin polymer-modified carbon fiber is at least one of a cycloolefin copolymer and a cycloolefin homopolymer.

4. The polypropylene composite material according to claim 1, characterized in that: In the cycloolefin polymer modified carbon fiber, the mass ratio of the hydroxylated carbon fiber, the coupling agent and the cycloolefin polymer is 1:(0.2-0.8):(0.2-0.8).

5. The polypropylene composite material according to claim 1, characterized in that: The polypropylene composite material also includes 1 to 10 parts of other additives.

6. The method for preparing the polypropylene composite material according to any one of claims 1 to 5, characterized in that: The method comprises the following steps: mixing the components, melt-extruding and granulating to obtain the polypropylene composite material.

7. Use of the polypropylene composite material according to any one of claims 1 to 5 in the preparation of automotive parts.

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